From: Will Deacon <will@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: kernel-team@android.com, Will Deacon <will@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Yu Zhao <yuzhao@google.com>, Minchan Kim <minchan@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Anshuman Khandual <anshuman.khandual@arm.com>,
linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org,
stable@vger.kernel.org
Subject: [PATCH 1/6] arm64: pgtable: Fix pte_accessible()
Date: Fri, 20 Nov 2020 14:35:52 +0000 [thread overview]
Message-ID: <20201120143557.6715-2-will@kernel.org> (raw)
In-Reply-To: <20201120143557.6715-1-will@kernel.org>
pte_accessible() is used by ptep_clear_flush() to figure out whether TLB
invalidation is necessary when unmapping pages for reclaim. Although our
implementation is correct according to the architecture, returning true
only for valid, young ptes in the absence of racing page-table
modifications, this is in fact flawed due to lazy invalidation of old
ptes in ptep_clear_flush_young() where we elide the expensive DSB
instruction for completing the TLB invalidation.
Rather than penalise the aging path, adjust pte_accessible() to return
true for any valid pte, even if the access flag is cleared.
Cc: <stable@vger.kernel.org>
Fixes: 76c714be0e5e ("arm64: pgtable: implement pte_accessible()")
Reported-by: Yu Zhao <yuzhao@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/include/asm/pgtable.h | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 4ff12a7adcfd..1bdf51f01e73 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -115,8 +115,6 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
#define pte_valid(pte) (!!(pte_val(pte) & PTE_VALID))
#define pte_valid_not_user(pte) \
((pte_val(pte) & (PTE_VALID | PTE_USER)) == PTE_VALID)
-#define pte_valid_young(pte) \
- ((pte_val(pte) & (PTE_VALID | PTE_AF)) == (PTE_VALID | PTE_AF))
#define pte_valid_user(pte) \
((pte_val(pte) & (PTE_VALID | PTE_USER)) == (PTE_VALID | PTE_USER))
@@ -126,7 +124,7 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
* remapped as PROT_NONE but are yet to be flushed from the TLB.
*/
#define pte_accessible(mm, pte) \
- (mm_tlb_flush_pending(mm) ? pte_present(pte) : pte_valid_young(pte))
+ (mm_tlb_flush_pending(mm) ? pte_present(pte) : pte_valid(pte))
/*
* p??_access_permitted() is true for valid user mappings (subject to the
--
2.29.2.454.gaff20da3a2-goog
next prev parent reply other threads:[~2020-11-20 14:36 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-20 14:35 [PATCH 0/6] tlb: Fix access and (soft-)dirty bit management Will Deacon
2020-11-20 14:35 ` Will Deacon [this message]
2020-11-20 16:03 ` [PATCH 1/6] arm64: pgtable: Fix pte_accessible() Minchan Kim
2020-11-20 19:53 ` Yu Zhao
2020-11-23 13:27 ` Catalin Marinas
2020-11-24 10:02 ` Anshuman Khandual
2020-11-20 14:35 ` [PATCH 2/6] arm64: pgtable: Ensure dirty bit is preserved across pte_wrprotect() Will Deacon
2020-11-20 17:09 ` Minchan Kim
2020-11-23 14:31 ` Catalin Marinas
2020-11-23 14:22 ` Catalin Marinas
2020-11-20 14:35 ` [PATCH 3/6] tlb: mmu_gather: Remove unused start/end arguments from tlb_finish_mmu() Will Deacon
2020-11-20 17:20 ` Linus Torvalds
2020-11-23 16:48 ` Will Deacon
2020-11-20 14:35 ` [PATCH 4/6] mm: proc: Invalidate TLB after clearing soft-dirty page state Will Deacon
2020-11-20 15:00 ` Peter Zijlstra
2020-11-20 15:09 ` Peter Zijlstra
2020-11-20 15:15 ` Will Deacon
2020-11-20 15:27 ` Peter Zijlstra
2020-11-23 18:23 ` Will Deacon
2020-11-20 15:55 ` Minchan Kim
2020-11-23 18:41 ` Will Deacon
2020-11-25 22:51 ` Minchan Kim
2020-11-20 20:22 ` Yu Zhao
2020-11-21 2:49 ` Yu Zhao
2020-11-23 19:21 ` Yu Zhao
2020-11-23 22:04 ` Will Deacon
2020-11-20 14:35 ` [PATCH 5/6] tlb: mmu_gather: Introduce tlb_gather_mmu_fullmm() Will Deacon
2020-11-20 17:22 ` Linus Torvalds
2020-11-20 17:31 ` Linus Torvalds
2020-11-23 16:48 ` Will Deacon
2020-11-22 15:11 ` [tlb] e242a269fa: WARNING:at_mm/mmu_gather.c:#tlb_gather_mmu kernel test robot
2020-11-23 17:51 ` Will Deacon
2020-11-20 14:35 ` [PATCH 6/6] mm: proc: Avoid fullmm flush for young/dirty bit toggling Will Deacon
2020-11-20 17:41 ` Linus Torvalds
2020-11-20 17:45 ` Linus Torvalds
2020-11-20 20:40 ` Yu Zhao
2020-11-23 18:35 ` Will Deacon
2020-11-23 20:04 ` Yu Zhao
2020-11-23 21:17 ` Will Deacon
2020-11-24 1:13 ` Yu Zhao
2020-11-24 14:31 ` Will Deacon
2020-11-25 22:01 ` Minchan Kim
2020-11-24 14:46 ` Peter Zijlstra
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201120143557.6715-2-will@kernel.org \
--to=will@kernel.org \
--cc=anshuman.khandual@arm.com \
--cc=catalin.marinas@arm.com \
--cc=kernel-team@android.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=minchan@kernel.org \
--cc=peterz@infradead.org \
--cc=stable@vger.kernel.org \
--cc=torvalds@linux-foundation.org \
--cc=yuzhao@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).